Chromatograph inlet with rotating septum

ABSTRACT

A septum inlet apparatus for chromatographs having a ported body and a septum disc carried by a rotatably mounted septum carrier driven by an electric motor through speed reduction gearing. The septum is rotatably moved a predetermined amount by operating the motor for a predetermined period of time to move a used portion of the septum out of operative position and bring into operative position an unused portion.

United States Patent Reid 1 51 June 27, 1972 [$4] Cl-lROMATOGRAPl-lINLET WITH ROTATING SEPTUM [72] Inventor: John 0. Reid, Monrovia, Calif.

[73] Assignee: Hamilton Company, Whittier, Calif.

[22] Filed: Dec. 18, 1969 [21] Appl. No.: 886,142

[52] vs. (:1. "73/422 oc, 73/211 151 1111. c1. ....G0ln 1/00, 0011131/08 153 mm ol'Senrch ..73/422 oc,23.1;141/a11;

[56] Relerenoes Cited UNITED STATES PATENTS 3,559,454 2/1971 Evans..73/23.1 3,566,697 3/1971 Vannus.............................73/422 GC2,644,452 7/1953 Brown ..215/38 X 3,223,123 12/1965 Young ..73/422 GC3,374,660 3/1968 McKinney et a1 ..73/23 1 3,482,450 12/1969 Harris, Sr.et al. ..73/422 GC 3,501,176 3/1970 Arms ..73/422 GC PrimaryExaminer-Louis R. Prince Assistant Examiner-Daniel M. Yasich Attorney-J.Carroll Baisch [5 7] AISTRACT A septum inlet apparatus forchromatographs having a ported body and a septum disc carried by arotatably mounted septum carrier driven by an electric motor throughspeed reduction gearing. The septum is rotatabiy moved a predeterminedamount by operating the motor for a predetermined period of time to movea used portion of the septum out of operative position and bring intooperative position an unused portion.

3 Claims, 4 Drawing Figures PATENTEDJUNP? 1272 3.672. 226

Jo/m 0. Rafa,

INVENTOR.

CHROMATOGRAPI-I INLETWITI-I ROTATING SEP'IUM CROSS-REFERENCE TO RELATEDAPPLICATION BACKGROUND OF THE INVENTION I Field of the Invention Thisinvention relates generally to inlets for chromatographs and relatesmore particularly to chromatograph inlets having a septum that can bequickly and easily moved to bring various pans thereof into operativeposition.

2. Description of the Prior Art Conventional inlets for chromatographshave various problems, disadvantages and operating difficulties. As iswell known, septums retain their sealing reliability for from six to teninjections and then must be replaced. When such septums are replaced,the chromatograph instrument must be shut down and there is, of course,an interruption of carrier gas flow and a loss of carrier gas while theused septum is removed from the inlet and a new septum installed. Then,there is a waiting period while the instrument regains its operatingtemperature after a shutdown. There is, also, always the danger that theoperator will have his fingers burned while changing the septum.

The Vannus Automatic Septum Changing Inlet provides septum changerwherein the septum disc is carried by a rotatably mounted rachet wheelhaving a plurality of annularly spaced outer ports which aresuccessively moved into alignment with a port of the body, there beingmeans for successively rotating the ratchet wheel to move said outerports respectively into alignment with the port in the body.

SUMMARY OF THE INVENTION The present invention has a body, forconnection with a chromatograph column, and ha a heater. A collarprovides thermal isolation from the body to the chromatograph panel. Aseptum carrier is provided with a Teflon O-ring serving as a secondaryseal, the septum being the primary seal. An electric motor effectsrotation of the septum carrier through speed reduction means, therebeing a needle guide offset from the axis of the septum carrier. Thereis spring loaded means which keeps the septum under compression andcompens tea for the thermal expansion of the septum under the operatingtemperature conditions of the chromatograph and inlet.

OBJECTS AND ADVANTAGES OF THE INVENTION It is an object of the inventionto provide an inlet for chromatographs having means for moving theseptum to bring unpunctured or unused portions, respectively, intooperative position as portions lose their sealing reliability by beingpunctured a number of times.

Another object of the invention is to provide a chromatograph inlethaving means for easily and quickly changing effective parts of aseptum.

Still another object of the invention is to provide an inlet of thischaracter that is simple in construction and reliable in operation.

A further object of the invention is to provide an inlet of thischaracter that has relatively few parts and is relatively inexpensive tomanufacture.

A still further object of the invention is to provide an inlet of thischaracter wherein the movement of the septum from station to station iseffected without shutting down the instrument.

Another object of the invention is to provide apparatus of thischaracter which eliminates interruption of carrier gas flow and loss ofcarrier gas.

Still another object of the invention is to provide apparatus of thischaracter which eliminates waiting for the instrument to regain itsoperating temperature after a shut down.

A further object of the invention is to provide a chromatograph inletapparatus that eliminates the danger of the operator burning hisfingers.

The characteristics and advantages of the invention are furthersufficiently referred to in connection with the following detaileddescription of the accompanying drawings, which represent oneembodiment. After considering this example, skilled persons willunderstand that many variations may be made without departing from theprinciples disclosed and I contemplate the employment of any structures,arrangements or modes of operation that are properly within the scope ofthe appended claims.

BRIEF DESCRIPTION OF THE DRAWING Referring to the drawings, which arefor illustrative purposes only:

FIG. I is a side elevational view of a chromatograph inlet embodying myinvention;

FIG. 2 is a sectional view thereof taken on line 2-2 of FIG. 1;

FIG. 3 is a top plan view; and FIG. 4 is a sectional view taken on line44 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly tothe drawings, the inlet comprises a body, indicated generally at 10, ofstainless steel, aluminum, or other suitable material. Body 10 is shownas being cylindrical but it may be of any other suitable shape. The bodyhas a cylindrical recess 12 in the upper end, with a short cylindricalboss 14 upstanding axially from the bottom of said recess 12. Boss 14has a longitudinally extending needle bore 16 of such diameter as tooperably receive the needle of a fluid measuring syringe, said needlebore 16 being offset from the axis of the boss 14.

Extending longitudinally from the lower end of the body 10, as shown inFIGS. 1 and 2, is an adaptor bore 18 which is in axial alignment withthe needle bore 16 but of greater diameter. An outer end portion 20 ofthe adaptor bore 18 is tapped for threadable reception of a columnfitting 22 at the end of a chromatograph column 23, said fittingcarrying a column adaptor 24 disposed in the adaptor bore I8, saidcolumn adaptor 24 being of smaller diameter than the adaptor bore 18,the inner end 26 of said column adaptor 24 clearing the inner end of theadaptor bore so that carrier gas can flow into the fluid flow passage 28of the column adaptor from the annular space 30 between the wall of theadaptor bore 18 and the external wall of the column adaptor. The fluidflow passage may flare at its inner end to facilitate insertion of theneedle.

The body 10 has a laterally extending tapped bore 32 for reception ofthe externally threaded end portion of a carrier gas fitting 34, apassage 36 extending from the inner end of the tapped bore 32 to providea connection with the annular flow passage 30 between the wall of theadaptor bore and the adaptor 24.

Body 10 also has a heater bore for an electric heater 38, of well knowncharacter, for heating the inlet body to the proper operatingtemperature.

There is a collar 40 having a radially extending annular flange 42 atthe upper end, said collar having a greater inside diameter than theexternal diameter of the body 10, the collar being of stainless steel,aluminum, or other suitable material. Collar 40 is positioned at theupper end of the body 10 and is secured in spaced relation thereby bysetscrews 44 disposed in tapped openings provided therefor in the collarand aligned tapped bores provided therefor in the body adjacent theupper end thereof. There may be any suitable number of such setscrewsbut three equally spaced about the collar and body are used. Thermalisolation of the collar from the body is providedbyhavingthecollarspacedfromthe body.

The flange 42 has an opening 46 therethrough of smaller diameter thanthe internal diameter of the collar 40, the upper end portion of thebody being received in said opening 46. Flange 42 also has openings 48therethrough for reception of screws 50 for securing the inlet to thechromatograph panel 52, there being tubular spacers 54 on said screws 50for properly spacing the outer (upper) end of the inlet from said panel.it is to be noted that the panel 52 has an opening 56 therein forreception of the body 10.

Within the recess 12, there is rotatably disposed a cup shaped septumretainer having a peripheral wall 60 and a bottom wall 62, said wallsdefining a recess 64. The bottom wall has an axial bore 624 therethroughin which is received the boss 14, the height of the boss being the sameas the thickness of the bottom wall 62 of the septum retainer so thatthe upper surface of said boss is in substantially the same plane as theupper surface of said bottom wall 62. The underside of the bottom wallhas an axial, annular groove about the axial bore in the bottom wall 62in which an O-ring is disposed to provide what is termed a secondaryseal between the septum retainer and the bottom of recess 12 of thebody. A septum 68 is press fitted, or otherwise secured in the recess 64of the septum retainer, and the under side of said septum sealinglyengages the top surface of boss 14 and comprises the primary seal, saidtop surface of said boss providing back-up means for the septum. Theseptum is of any suitable, well known character, various septums beingavailable on the market. However, the septum shown is laminated, therebeing a relatively soft central layer of silicone rubber with layers ofharder silicone rubber secured to each side of said central layer. Theseptum is self-sealing.

A gear subassembly, indicated generally at 72, comprises a gear 74having a hub 76 from which project a pair of oppositely disposed radialpins 78. Hub 76 is received within the recess 64 of the septum retainerand rests on the septum, the pins 78 being received within the notches70 and are disposed intermediate the top and bottom thereof, and cantake care of expansion and contraction of the septum. Also, thisconnection between the septum retainer and the gear subassembly 72provides means whereby the septum retainer is rotated with rotation ofthe gear subassembly, to thereby move and thereby replace unpuncturedportions of the septum for punctured portions, as described more fullyhereinafter.

There is a motor mount and needle guide, indicated generally at 80,which comprise a generally Tshaped plate 82, the stern of the T having abore 84 therein, there being a flange 88 at the lower end of the bore 84defining an opening 90 in which an electric motor 92 is disposed. Themotor is secured in operating position by screws 94, three screws spacedannularly apart relative to the bore 84 being used.

Plate 82 has a U-shaped opening 96 in the cross part of the T leaving atongue 98 which has an opening therein for reception of the enlargedhead 100 of a needle guide 102. The opening 96 serves to minimize heattransference to the tongue 98. The needle guide is disposed in an axialbore 104 through the hub 76 of the gear subassembly 72, and friction isminimized between the upper end of the hub 76 and its gear by a thrustball bearing assembly 108 disposed on the needle guide 102.

Motor mount and needle guide 80 are secured to the flange 42 by means ofoppositely disposed screws 110 disposed in openings 112, providedtherefor in the plate 82 adjacent the free ends of the cross part of theT, the lower ends of said screws being threadably received in tappedbores provided therefor in said flange 42. These screws are ofsubstantial length and have coil springs 114 disposed thereon above theplate 82. The lower ends of said springs are received in springretaining counter bores at the upper ends of said openings 2. The upperends of said springs abut against the heads l 16 of said screws 110 sothat said springs react between said screw heads 116 and the bottoms ofthe counter bores of openings 112, and yieldingly urge the platedownwardly so that the lower end of the needle guide is pressedsealingly against the upper surface of the septum. The springs 114 allowmovements of the plate and, hence, the needle guide, with expansion andcontraction of the septum.

The needle guide is provided with a needle guide passage 120, flared atits outer end 121. Needle guide passage is parallel to but radiallyoffset from the axis of the needle guide and axis of the septum andseptum retainer, when the above described parts of the inlet areoperably assembled. Also, when said parts are thus assembled there is agear [22 on the rotatable shaft of the electric motor 92 which mesheswith the gear 74, gear 122 being of much smaller diameter than thediameter of the gear 74, so that when the motor is energized there is aspeed reduction that results in a slow rotation of the septum retainerand septum.

Thermocouple holes 125 are provided in the body 10, and there are, also,therrnooouple holes, not shown, in the collar, motor mount and needleguide.

Since the needle passage 120 in the needle guide and the needle bore 16are offset from the axis of the septum retainer, septum rotation thereofby the motor 92 will cause an annular part of the septum spaced from theaxis thereof to be brought under or into alignment with the needlepassage 120 and needle bore 16.

OPERATION Carrier gas is supplied through a conduit and fixture 34therefor. The carrier gas flows through the annular passage 30 betweenthe wall of the adaptor bore 18 and the exterior of the column adaptor24, past the upper free end of said column adaptor, into the space 132at the end of said column adaptor and into the fluid flow passage 28 ofthe column adaptor, and, hence, to the chromatograph column 23.

With the inlet at operating temperature, the operator inserts the needleinto the needle passage 120, through the septum, needle bore 16 and intothe fluid flow passage 28 of the adaptor. The operator then injects thesample. The carrier gas continues to flow into and through the fluidflow passage 28 of the adaptor, since said fluid flow passage is largerin diameter than the outside diameter of the needle. As the sample isinjected into the fluid flow passage 28, it is entrained by the carriergas and carried along into the chromatograph column.

After a number of injections, the sealing reliability of the septum islost.

The part of the septum that has been repeatedly punctured and lost itssealing reliability is then rotated out of alignment with the needlepassage 120 and needle bore 16 by closing switch 126 of the electriccircuit for the motor, wires I28 and 130 of said electric circuit beingconnected to a suitable source, not shown, of electric power. The motoris operated for a predetemiined period of time to rotate the septum intoalignment with said needle passage 120 and needle bore 16. An example ofthe amount of rotation of the septum to effect the above describedchange is 0.06545 inch, the motor being operated but a few seconds toeffect this amount of rotation.

I claim:

I. A septum inlet apparatus for chromatographs, comprismg:

A. a body having an adaptor bore therein adapted to receive carrier gas;

B. a column adaptor operably disposed in said adaptor bore, said columnadaptor having a fluid flow passage therein adapted to be connected tothe column of a chromatop C. a rotatable septum carrier operably carriedby said body;

D. a septum carried by said septum carrier and rotatable therewith;

a needle guide having a needle guide passage therethrough parallel tothe axis of said septum carrier but radially offset from said axis, thefluid flow passage in the column adaptor being aligned with the needleguide passage;

F. resilient means for applying yielding pressure to the outer side ofsaid septum;

G. means for rotating said septum carrier;

H. the body having a cylindrical recess in one end in which the septumcarrier is rotatable, said septum carrier being cup-shaped and having aperipheral wall and an end wall having an axial bore therethrough, saidend wall having an axial groove in the bottom thereof concentric withsaid bore; and a secondary seal in said groove providing a seal betweenthe septum carrier and the bottom of the recess in the body.

2. The invention defined by claim 1, wherein the peripheral wall of theseptum carrier has a pair of oppositely positioned radial notches; andthe means for rotating the septum carrier includes a gear having a hub,a pair of oppositely extending radial pins carried by said hub andslidingly disposed in said notches to permit axial movement of said hubrelative to said septum carrier.

3. The invention defined by claim 2, wherein there is a cylindrical lugupstanding from the bottom of the recess in said body and extending inthe axial bore in the bottom wall of the septum carrier, the free end ofsaid lug being flat and normal to the axis of said lug and providing abacking for the sep tum, said lug having a needle bore therethroughoffset from the axis of said lug and in alignment with the needle guidepassage of the needle guide, said needle bore also being in alignmentwith the fluid flow passage of said column adaptor.

1. A septum inlet apparatus for chromatographs, comprising: A. a bodyhaving an adaptor bore therein adapted to receive carrier gas; B. acolumn adaptor operably disposed in said adaptor bore, said columnadaptor having a fluid flow Passage therein adapted to be connected tothe column of a chromatograph; C. a rotatable septum carrier operablycarried by said body; D. a septum carried by said septum carrier androtatable therewith; E. a needle guide having a needle guide passagetherethrough parallel to the axis of said septum carrier but radiallyoffset from said axis, the fluid flow passage in the column adaptorbeing aligned with the needle guide passage; F. resilient means forapplying yielding pressure to the outer side of said septum; G. meansfor rotating said septum carrier; H. the body having a cylindricalrecess in one end in which the septum carrier is rotatable, said septumcarrier being cupshaped and having a peripheral wall and an end wallhaving an axial bore therethrough, said end wall having an axial groovein the bottom thereof concentric with said bore; and a secondary seal insaid groove providing a seal between the septum carrier and the bottomof the recess in the body.
 2. The invention defined by claim 1, whereinthe peripheral wall of the septum carrier has a pair of oppositelypositioned radial notches; and the means for rotating the septum carrierincludes a gear having a hub, a pair of oppositely extending radial pinscarried by said hub and slidingly disposed in said notches to permitaxial movement of said hub relative to said septum carrier.
 3. Theinvention defined by claim 2, wherein there is a cylindrical lugupstanding from the bottom of the recess in said body and extending inthe axial bore in the bottom wall of the septum carrier, the free end ofsaid lug being flat and normal to the axis of said lug and providing abacking for the septum, said lug having a needle bore therethroughoffset from the axis of said lug and in alignment with the needle guidepassage of the needle guide, said needle bore also being in alignmentwith the fluid flow passage of said column adaptor.